Clean Tank Research Articles

Retention of Tritium in Freshwater Marsh Organisms

Tritium retention for snails (Viviparus malleatus, Lymnaea exilis), tadpoles (Rana pipiens), crayfish (Procambarus blandingi), carp (Cyprinus carpio), and bluegill sunfish (Lepomis macrochirus) was determined over a 48-hour period under laboratory conditions. The organisms were maintained in tritiated water (0.19 μci/ml) for 48 hours prior to transfer to clean flowing-water tanks, and subsequent sampling. Curves for tritium retention were resolved into short and long components. Most of the tritium (96.2 percent or more) was lost in the short component. There were significant differences in the turn-over rates of tritium between species. The half-life of tritium in Viviparus exposed to tritium in food under field conditions was longer than the half-life in Viviparus exposed to tritiated water in the laboratory. The differences in half-life were probably due to differences in exposure time and the type of exposure. The half-life of tritium in mallard ducks exposed to tritium for 2 and 4 weeks at Navarre Marsh was approximately 15 days.

USE OF A GRAVITY TYPE OIL SEPARATOR FOR TANKER OPERATIONS

ABSTRACT The need to control the oil content in ballast and tank cleaning discharges to meet increasingly stringent seawater pollution standards has led to the development of a gravity type separator capable of handling up to 300 tons/hour of oily ballast water. When properly handled these separators enable the tanker operator to clean tanks and process oily ballast with an oil content of up to 100% without fear of contamination of the seas. This continuous and automatic operation is unaffected by normal movements. The recovered oil is available for burning as fuel aboard ship, “load-on-top” or disposal ashore. Separators of this type have been in use on three 70,000 DWT ships, for periods of one to three years. On typical voyages a ship of this size can recover enough slop oil to provide one day or more of bunkers if the ship is equipped to burn the recovered oil. The ship's crew is trained to carry out analysis of the oil to determine if the oil can be burned onboard immediately following separation or must be treated to drop out salt and/or water prior to burning. Several typical ballast voyages using the separator will be discussed. The overboard discharge of water from the separator is analyzed to assure compliance with current pollution regulations and a means to shunt the overboard discharge into a holding tank is employed if the oil content is too high. Limitations and possible improvements of this type of separator will also be presented.

Ultrasound and vortex stirring as bacteriological sampling methods for foods.

Summary.The efficiencies of an ultrasonic cleaning tank (insonation) and a vortex stirrer for bacteriological sampling of foods were compared with a standard homogenization method. Insonation gave good recovery of micro‐organisms in a limited range of foods, and its main advantage was the very low debris content of the resultant suspension. Vortex stirring was a much more useful method for routine work, combining convenience and rapidity of sample preparation with low running costs, low noise level and easily pipettable suspensions. The high concentration of organisms obtained by vortex stirring may aid detection of low levels of contamination.

MOBILE RECLAIMER FOR TRANSFORMER OILS

A new large oil reclaimer was recently completed by The Hilliard Corporation, 100 W.Fourth St., Elmira, New York, U.S.A. This was Model 500‐X Duplex Hyflow reclaimer designed for the purification of transformer insulating oils and is mounted on a flat bed trailer, illustrated. The unit removes water, sludge, acids and other oil oxidation products, dissolves paint, bushing compound, metallic soap and other contaminants. The 500 gal/hour reclaimer incorporates a 375 gal. dirty oil storage tank, a 275 gal. clean oil storage tank, a 50 kW petrol engine driven electric generating plant, hose reels and storage space for filter material. Unique features are central electric and valve control panels operating oil and vacuum pumps to provide easy reading of pressures, temperatures, fluid levels and direction of flow. The single cartridge fuller's‐earth filters are handled by a telescoping electric hoist.

Electrolytic cleaning of rectifier tanks

IN UNDERTAKING a general overhaul of a mercury arc rectifier at periodic intervals, the problem of interior cleaning of the tanks always has been a troublesome one. The tank in use usually has accumulated considerable contamination of loose material eroded from the elements of the rectifier. In addition to a dirty condition of the mercury pool, a quite hardened black slick scum may cover a large area of the tank walls. After removing all the interior parts, past practice has been either to sand-blast or wire-brush the tank walls and bottom in an effort to furnish a clean tank for the introduction of the new mercury needed for further operation.